Abstract

The UOE process is widely recognized as an effective approach to manufacture large-diameter submerged-arc welding pipes. During the UOE process, the plate is crimped along its edge, pressed into U and O shape, welded closed and then expanded to obtain a circular pipe. In this study, the mechanical properties tests are carried out on the API X80 pipeline steel to establish the constitutive model. A two-dimensional finite element model of the UOE forming process is established under plane strain assumption. The deformed geometry of different forming steps and the distribution of equivalent plastic strain are obtained. The model is validated in practical manufacturing by comparing the forming quality, which shows a significant coherence in their geometric configurations. In particular, the effect of process parameters on the forming quality is analyzed. Those parameters are the yield strength of the plate, the location of C-die, the initial location of U-rollers, the displacement of U-rollers, the location of V-anvil, the final spacing between O-punch and O-die. The main forming quality includes the opening after O-forming, the ovality after pre-welding and expansion. The relation curves of parameters versus forming quality are obtained and illustrated.